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| Author(s): |
Raíssa Sepulvida
Total Authors: 1
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| Document type: | Master's Dissertation |
| Press: | Rio Claro. 2020-12-02. |
| Institution: | Universidade Estadual Paulista (Unesp). Instituto de Biociências. Rio Claro |
| Defense date: | 2020-11-04 |
| Advisor: | Laurence Marianne Vincianne Culot; Carlos Augusto Peres |
| Abstract | |
Seed dispersal by animals is an important process for the maintenance of biodiversity in tropical forests. Zoochory is of great importance for many plant species as it increases seedling recruitment probability. Seed handling by frugivores (seed cleaning and removal away from conspecifics) has the potential to reduce seed mortality and increase germination and recruitment success. However, it is still unknown how much these effects vary according to fruit/seed traits. Indeed, we can expect that seed cleaning affects more positively fleshy-pulp fruits since this treatment reduces the pathogen infestation that is more likely to occur in such fruits. Seed removal from conspecific trees helps to escape the density-dependent mortality and its effect might thus be stronger for species suffering high negative plant-soil feedback. Here, we investigated how seed cleaning and removal away from conspecifics affect the germination, seedling emergence and survival of three species with distinct traits: Castilla ulei (Moraceae; fleshy pulp hardly adhered to the soft seed), Hymenaea parvifolia (Fabaceae; hard-wood pod, farinaceous pulp and hard seed) and Byrsonima arthropoda (Malpighiaceae; fleshy pulp around a hard-wood pyrene with 2-3 seeds). We also estimated how much the seed handling by frugivores changes the seed dispersal effectiveness (SDE - estimated as the proportion of seed/seedling surviving until the end of the study) of plants compared to the expected reproductive success in absence of seed dispersers. We conducted a field experiment in the southern Brazilian Amazon (terra firme forest), Mato Grosso, applying the combination of treatments to seed species: cleaned seeds, seeds with pulp, under and away conspecific trees. Seed cleaning significantly increased the germination, seedling emergence success and had a weak positive effect on survival of C. ulei while removal away from conspecifics had only a weak negative effect on seedling emergence. Since none of undispersed seeds survived, seed cleaning by frugivores increased C. ulei SDE asymptotically. Seed deposition under heterospecific trees significantly increased the germination success of H. parvifolia, but weakly. Neither removal nor seed cleaning affected seedling emergence and survival. Despite the positive (but weak) effect of seed removal away from conspecifics on H. parvifolia germination, it was not sufficient to positively affect seed/seedling survival, which was actually decreased by up to 25%. B. arthropoda did not germinate during the study period, and we found that seed cleaning decreased seed survival, consequently decreasing the SDE by up to 75%. Our results suggest that seed handling and removal from conspecifics affect the plants differently according to the life stages and the plant species. Such discrepancy may be explained by the traits of fruits and seeds and further research involving plant responses to seed handling according to functional traits would help to better predict the effect of the absence of dispersers on forest regeneration. (AU) | |
| FAPESP's process: | 18/11358-7 - Linking plant-soil feedback to the effect of frugivore treatment on seed germination |
| Grantee: | Raíssa Sepulvida Alves |
| Support Opportunities: | Scholarships in Brazil - Master |